You must do this via a 'Credits' menu on your title screen where you show a list.   

I have a very specific question about the above line. 

Is the credits menu ONLY allowed on the TITLE screen. If I were to make a very obvious button that takes you to a credits screen (in addition to the README) would that be allowed?  I'm planning the title screen and it is looking overcrowded. 

Anywhere in the title or main menu system of the game should be fine.

So for example, it'd be ok to have a title menu like:

Continue

New Game

Options

And then put Credits under the options sub menu like this:

Sound Options

Video Options

Input Options

Credits

That would be fine.  

This is just an example, however you want to lay things out is fine, just so long as the credits are easy to find from the title screen you should be fine.